Method of making spark-plug insulators



f .w 5 E w l M MJ M H0 $11. 5,555,515 i I JAA) l. SCHARL.

METHOD 0F MAKING SPARK PLUG INSULATORS.

APPHCATWN FILED DEC- !B. l9l8.

Pand June 15, 1920.

JOHN sensei., or NEW Yoan, ujf.,

PATENT oFFtcE.

ASSIGNOR TO GENERAL CERAMICS COMPANY, OF

JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

METHOD OF IVIAI'IINGr SPARK-PLUG INSULATORS.

Specification otLetters Patent.

Patented J une 15, 1920.

Application mea December 1s, 191s. serial No. 267,240.

T o all whom it may Concern.'

Be it known that I, JOHN Senaat, a citizen of Hungary, and a resident of New York city, in the county and State of New York, have invented a new and useful Method of Making Spark-Plug Insulators, of which the following is a specification.

This invention relates to a method of making an insulator which is designed to form a component part of a spark plug and which possesses numerous advantages over the porcelain insulators now generally used, particularly for the reason that it not liable to crack under sudden changes of temperature. `Such changes are frequently encountered by flying machines.

In the accompanying drawing:

Figure 1 is a diagrammatic sectional c levation of an apparatus for carrying my invention into e ect; C

Fig. 2, a vertical cross section showing the mold open;

Fig. 3, a similar section showing the mold closed;

Fig. 4, a horizontal section showing the electrodes;

Fig. 5, a diagrammatic cross section of a modification, and,

Fig. 6, a. perspective view of an insulator complete.

The body of the insulator 5 (Fig. 6) has the conventional or any other shape de` sired, and is provided with a longitudinal bore for the reception of one of the terminais.

I propose to form the insulator of the material known as fused silica or silica glass, which is generally obtained by subjecting a quantity of quartz sand to a high temperature in an electric furnace so as to fuse the sand into a homogeneous body.

In order to form the insulator from this material, I use an electrically heated mold formed of an upper section (l, and a lower section 7. The mold may be operated in suitable manner (not shown) and is provided with rods Sengaging tubular guides t). rl`he contour of the mold is such as to form the body 5 together with the usual collar 10, lwhile the edges of the mold are beveled as at 11, to discharge the overflow.

Centered between the mold sections is a pair of divided parallel spindles 12, which are spaced from each other and are proyided with holders 13. The spindles are mtergeared at l-t, andV may'bexsimultaneously rotated' by a crank handle 15, al small motor, or in other manner. 'pon a' rock shaft 1G (operated in suitable manner, not shown) is mounted a pair of bent arms 1T having hook shaped ends 18 that are adapted to grasp a. wooden or other core 19, the correlation of the parts being such that when the arms are swung up, they will cenv ter the core betY en spindles l2, and in parallelism therewith.

The apparatus described forms part of or directly adjoius an electric furnace, the drawing showing au are furnace having three electrodes 2U that face and heat the material mounted upon the spindles 12.

In use, a pair of fused quartz tubes, rods, plates, or similar bodies Q1 are fitted into the holders i3 of spindles 12, so that such tubes assume a spaced parallel relation. Upon the ends of tubes 21, is slipped a pair of baille plates 22 that confine the heat to the central portions thereof. The spindles are turned to rotate the tubes and the current is turned ou, to reheat the tubes, until they heroine soft or plastic, whereupon the spindles are arrested and the current is shut oil". A core 1S) fitted into arms 17, is carried between the softened tubes` by the turning shaft lil. This core'consists preferably of a stick of wood or other combustible material which may be treated with asbestos or other liquid which retards the combustion. The molds 6, 7 are closed to unite the tubes 21 into a single body, and to impart to such body the desired contour of `the insulation 5. During this shaping, the core 19 will be eventually consumed and in this way the insulation is made tubular or pro vided with the axial bore required for the reception of one of the spark plug termir nais. Should the core for some reason not be entirely consumed, it may be drilled out with little expense.

After the mold is opened, the finished insulation is removed, and after being cooled is ready to be incorporated into the spark plug.

lVith the embodiment illustrated in Fig. 5, the mold'sections 23 are out of vertical alinement with the spindles carrying the fused quartz rods 24, and are separated therefrom by a movable baille plate 25. Op-

posite the rods 24, are Ine electrodes 26, while the core 2T is adapted to be centered between the mold sections. 'ith this con struction, thtl quart'/A rods 24 are heated, the batllv plate 2.7 is withdrawn, the spindles are shifted to a position between the mold sec tions, the core is introduced between the quartz rods, and the mold sections are closed as previously described, to produce the tubular insulation desired.

In lieu of usingr a comlnistible core, a rod of platinum, tungsten, or other metal hav ing n. high melting point may be used. Such a rod should be drawn out quickly after the molding operation has been finished and before the tube has set.

If desired, the silica glass initially operated upon by my process, may contain a small percentage of a flux, so as to increase its fusihility.

I claim:

1. In the lnethod of making a` spark plug insulator, that step which consists in re-fusing a silica glass body to render the same plastic and then folding such plastic body upon a core.

2. In the method of making a spark plug insulator, that step which consists in re-fusing a silica glass body to render the same plastic and then folding such plastic body upon a combustible core.

3. The method of making a spark plugr insulator which consists in rotating a pair of silica glass bodies, heating the same and then uniting them into a single body by molding them.

4. The method of4 making a spark plug insulator which consists in rotating a pair of silica glass bodies, heatin r the same,l '111- trodueing a core between tie bodies and then moldingr them upon the core.

5. The method of making a spark .plug insulator which consists in rotating a pair of silica glass bodies, heating the same, introducing a combustible core between the bodies and then molding the bodies upon the core.

JOHN SCHARL. 

